This invention relates to a distillation process particularly to the separation of higher boiling impurities from liquefied gases by rectification, and associated apparatus.
Various condensation processes are used advantageously to separate gaseous components from raw gases, for example to obtain CO from steam reformer gases. Gases produced by a condensation process frequently contain trace amounts of light (lower boiling) and heavy (higher boiling) components which are detrimental to certain uses of the liquefied gases, e.g., downstream synthesis operations. The light components can be separated simply and economically, for example, by stepwise condensation and expansion, as has been described, for example, in published German application No. P 33 13 171.6 (corresponding to assignee's U.S. application Ser. No. 600,059, filed Apr. 12, 1984) for the separation of an H.sub.2 -CO mixture. In contrast, the separation of heavy components generally requires a relatively high expenditure in energy as well as apparatus.